Nearly all fission reactions utilizing the uranium isotope, U.sub.235, require a concentration of the U.sub.235 isotope greater than in the naturally occurring state. The process of enrichment whereby the concentration of U.sub.235 in natural or depleted uranium is raised to a desired level has been achieved in the past by many techniques which generally operate to separate U.sub.235 from the other uranium isotopes, chiefly U.sub.238, on the basis of its slight chemical or mass difference. Enrichment according to these techniques often requires cascaded processing using a sequence of repeated applications of the same steps, each step providing a slight increase in the concentration of the desired U.sub.235 isotope.